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triple point
triple pointn. The temperature and pressure at which a substance can exist in equilibrium in the liquid, solid, and gaseous states. The triple point of pure water is at 0.01 degrees Celsius and 4.58 millimeters of mercury and is used to calibrate thermometers.triple point n (Chemistry) chem the temperature and pressure at which the three phases of a substance are in equilibrium. The triple point of water, 273.16 K at a pressure of 611.2 Pa, is the basis of the definition of the kelvin tri′ple point′
n. the particular temperature and pressure at which the solid, liquid, and gaseous phases of a given substance are all at equilibrium with one another. [1870–75] triple pointThe intersection of the incident, reflected, and fused (or Mach) shock fronts accompanying an air burst. The height of the triple point above the surface, i.e., the height of the Mach stem, increases with increasing distance from a given explosion.triple pointThe conditions of temperature and pressure at which the three phases of a substance (solid, liquid, and gas) are in equilibrium.triple point
triple point Chem the temperature and pressure at which the three phases of a substance are in equilibrium. The triple point of water, 273.16 K at a pressure of 611.2 Pa, is the basis of the definition of the kelvin Triple Point in thermodynamics, the point on a phase diagram at which three different phases of a substance can coexist in equilibrium. It follows from the phase rule that there cannot be more than three phases in equilibrium in a substance consisting of one chemical element or compound, that is, a one-component system. The three phases may be, for example, the solid, liquid, and gas phases or, as in the case of sulfur, the liquid phase and two al-lotropes of the crystalline phase. The phases can coexist only for specific values of temperature T and pressure p, which determine the coordinates of the triple point on the p-T diagram. For example, for carbon dioxide the triple-point temperature Ttp = 216.6°K, and the triple-point pressure ptp = 5.12 atmospheres. At the triple point of water, which is the fundamental fixed point of the absolute thermodynamic temperature scale, Ttp = 273.16°K (exactly), and ptp = 4.58 mm Hg. triple point[′trip·əl ′pȯint] (physical chemistry) A particular temperature and pressure at which three different phases of one substance can coexist in equilibrium. triple point
point [point] 1. a small area or spot; the sharp end of an object.2. to approach the surface, like the pus of an abscess, at a definite spot or place.3. a tapered, pointed endodontic instrument used for exploring the depth of the root canal in therapy" >root canal therapy; called also root canal point.point A a radiographic, cephalometric landmark, determined on the lateral head film; it is the most retruded part of the curved bony outline from the anterior nasal spine to the crest of the maxillary alveolar process.absorbent point in root canal therapy, a cone of variable width and taper, usually made of paper or a paper product, used to dry or maintain a liquid disinfectant in the canal. Called also paper point.point B a radiographic, cephalometric landmark, determined on the lateral head film; it is the most posterior midline point in the concavity between the infradentale and pogonion.boiling point the temperature at which a liquid will boil; at sea level the boiling point of water is 100°C (212°F).cardinal p's 1. the points on the different refracting media of the eye that determine the direction of the entering or emerging light rays.2. four points within the pelvic inlet— the two sacroiliac articulations and the two iliopectineal eminences.craniometric p's the established points of reference for measurement of the skull.dew point the temperature at which moisture in the atmosphere is deposited as dew.far point the most remote point at which an object is clearly seen when the eye is at rest.point of fixation 1. the point or object on which one's sight is fixed and through which the axis opticus passes.2. the point on the retina, usually the fovea, on which are focused the rays coming from an object directly regarded.freezing point the temperature at which a liquid begins to freeze, for water, 0°C (32°F); it is often used interchangeably with point" >melting point, but should be used for substances being cooled while melting point is reserved for substances being heated.gutta-percha point gutta-percha cone.ice point the true melting point of ice, being the temperature of equilibrium between ice and air-saturated water under one atmosphere pressure.isoelectric point (pI) the pH of a solution in which molecules of a specific substance, such as a protein, have equal numbers of positively and negatively charged groups and therefore do not migrate in an electric field.J point on an electrocardiogram, the junction between the end of the QRS segment and the beginning of the ST segment.jugal point the point at the angle formed by the masseteric and maxillary edges of the zygomatic bone; called also jugale.lacrimal point a small aperture on a slight elevation at the medial end of the eyelid margin, through which tears from the lacrimal lake enter the lacrimal canaliculi. See also lacrimal apparatus.point of maximal impulse the point on the chest where the impulse of the left ventricle is sometimes felt or seen most strongly, normally in the fifth costal interspace inside the mammillary line.McBurney point a point of special tenderness in appendicitis, about 4 to 5 cm from the right anterior iliac spine on a line between the spine and the navel; it corresponds to the normal position of the appendix.  McBurney's point is located midway between the anterior iliac crest and the umbilicus in the right lower quadrant. From Ignatavicius and Workman, 2002.melting point (mp) the minimum temperature at which a solid begins to liquefy; see also point" >freezing point.near point the nearest point of clear vision, the absolute near point being that for either eye alone with accommodation relaxed, and the relative near point being that for the two eyes together with employment of accommodation.nodal p's two points on the axis of an optical system situated so that a ray falling on one will produce a parallel ray emerging through the other.paper point absorbent point.pressure point 1. a point of extreme sensitivity to pressure.2. one of various locations on the body at which digital pressure may be applied for the control of hemorrhage.  Locations of pressure points. Shaded areas show the regions in which hemorrhage may be controlled by pressure at the points indicated.root canal point point (def. 3).silver point in therapy" >root canal therapy, a tapered and elongated silver plug that is cemented into the canal as a filling. Called also silver cone.trigger point a spot on the body at which pressure or other stimulus gives rise to specific sensations or symptoms.triple point the temperature and pressure at which the solid, liquid, and gas phases of a substance are in equilibrium.tri·ple pointthe temperature at which all three phases (that is, solid, liquid, and gas) are in equilibrium; the triple point of water (273.16 K) is a fundamental fixed point in temperature scales.FinancialSeePointThesaurusSeepoint |